After 21 years as a cop, spanning seven seasons on “Homicide: Life on the Street” and 14 seasons on “Law & Order: Special Victims Unit” — plus guest appearances on series ranging from “The Wire” to “Arrested Development” — Richard Belzer’s conspiracy-prone cop is hanging up his SVU badge on Wednesday’s episode (9 p.m./Ch. 4).

But more than the end of his service, it’s closure for the iconic detective, who’s appeared in more series and lasted longer than any other TV character in history.

“Personally, I think it’s going to be like an open wound” without Belzer on “SVU,” says Dean Winters, who plays Detective Brian Cassidy, Munch’s first partner when he made the move from Baltimore — after “Homicide” was cancelled — to the New York-based “Law & Order.”

During a brief guest stint on “Homicide,” Winters became friends with Belzer, and says the lanky comedian is the reason he was hired for “Law & Order.”

The distinctive dark clothing, the dour expression, the shaded sunglasses — “He looks like he sleeps upside down in his closet,” notes Winters — made the surly Munch a memorable character. He was based on a real-life Baltimore detective, Jay Landsman, who was featured in David Simon’s book “Homicide: A Year on the Killing Streets,” which was the origin for the NBC series which aired from 1993-99.

In fact, much of Munch’s longevity can be attributed to the enduring influence of “Homicide” and “Law & Order” on the TV landscape: Simon went on to write for “The Wire” (Munch appeared in the in a bar scene in the fifth season).

The short-lived cop series “The Beat” (Munch showed up in one episode) was produced by “Homicide’s” Tom Fontana, who regularly exchanged characters on his series with his friend Dick Wolf. Wolf, in turn, produced the “Law & Order” franchise, which resulted in multiple opportunities for Munch to log additional screen time.

But after all those years of service, in true “L&O” low-key style, Munch’s retirement was mentioned as an afterthought in last week’s episode. Captain Cragen (Dann Florek) informed Benson (Mariska Hargitay) that the wisecracking detective put in his papers because of a particularly depressing case in which a white celebrity chef got away with shooting an innocent black teen.

This week promises at least a send-off party, with Munch ditching his regular mortician look for a white-jacket tux.

Det. Munch dons a white tux during his retirement episode.Photo: NBC

So what is Belzer doing after years of playing a cynical cop solving grisly cases and adding his gallows humor to murder scenes?

He’s living in the French countryside, according to Winters.

“I went to visit Richard in France in June, and he has this incredible estate,” Winters says. “I understand why he won’t continue doing ‘SVU.’ [The estate] was built in the 1100s, and has this 200-foot waterfall.

“I’ve never seen anything like it.”

But to imagine life on “SVU” without Munch is unthinkable, according to Winters.

“I think it would be irresponsible to never bring him back,” Winters says. “It’s like taking a flavor out of a really great bowl of soup.”